A distributed services environment is one that provides services to end users via a number of discrete and collaborating processing points, often referred to as agents, that interact to provide the services. A common example of a distributed service is providing simultaneous ringing in response to an incoming call. When one telephone is answered, the others will stop ringing. In a more complex example, called a multiple appearance directory number (MADN) environment, a group of telephones act in concert to answer an incoming session, and may subsequently transfer possession of the session to one or more of the telephones in the group. Distributed services also allow the collaboration of media-specific devices where two or more devices having different media capabilities collaborate to control a single media session. A distributed services environment may provide group services, such as automatic call distribution (ACD), MADN services, hunt group behavior, trunk selection, multimedia conferencing, and the like. Call distribution services allow groups of agents to service calls from an incoming pool of queued calls in a fair or otherwise specified manner. Hunt group or trunk selection allows calls to be accepted when possible by a limited facility, if there are sufficient resources available. In general, distributed telecommunications services can be defined as either structured or amorphous, wherein structured services imply that all participants in a group are not equal, have different roles in the services, or have a hierarchical relationship in execution of the service. Amorphous services are those where the participants in the group are substantially equal and have substantially identical roles.
In a distributed services environment, the multiple agents involved in providing a particular service need to exchange information amongst each other as well as discover the identity and the ability of both users and agents to participate in a specific service. In general, agents need to be able to declare their existence on the network, discover other participants, such as users and agents, for a given service, and exchange state information between active and discovered agents. Unfortunately, there is no uniform, standards-based manner in which to achieve such interaction at an applications level. Accordingly, there is a need to provide distributed services using uniform, application-level protocols that permit diverse implementations of distributed service agents to create and provide distributed services.